The solar-stellar connection in the era of ALMA

The aim of this splinter session at the Cool Stars 19 meeting in Uppsala, Sweden, 2016, is to bring together solar and stellar astrophysicists for discussing how ALMA could be used to study the solar-stellar connection.

Date: Thursday, June 9th, 2016

Scientific rationale

The Atacama Large Millimeter/submillimeter Array's (ALMA) impressive capabilities such as high spatial, temporal, and spectral resolution and high sensitivity are a true leap forward in the sub-/millimeter range. ALMA has already produced interesting results for a wide range of topics in astrophysics, including observations of α Centauri, the nearest stellar system to us. Also, the extreme end of the lower main sequence, incl. brown dwarfs, is a very active topic now to which ALMA observations will contribute.

ALMA can also observe the Sun and the data and experience gained from solar test campaigns have already demonstrated ALMA’s great potential for observations of the Sun. In particular, millimeter radiation offers indicators for stellar activity and for the dynamics and structure of stellar chromospheres, which are much easier to interpret than commonly used indicators like Hα, Ca II or Mg II lines. These diagnostic tools can be applied to observations of stars and the Sun, where spatially resolved observations of the Sun are complementary to stellar observations covering large parameter ranges. ALMA’s impressive capabilities enable us therefore to reevaluate stellar activity by means of comparative solar-stellar studies.

The aim of this session is to promote this unique scientific opportunity and to bring together solar and stellar astrophysicists with complementary background and expertise such as radio and millimeter observations, optical/UV observations and numerical simulations. Discussing potential synergies and strategies for stellar and solar observations with ALMA is very timely in view of solar observing becoming available from October 2016. This session is intended to contribute to developing a common understanding on how to best proceed together addressing the solar-stellar connection with the help of ALMA and thus, in the long run, contributing to advancing our understanding of solar/stellar activity with implications for stars in general, incl. stellar magnetism and dynamos and their role as host stars for extra-solar planets.